Date: Mar 6, 2013 5:54 AM
Author: David Park
Subject: Re: Mathematica and Lisp
Reverse the order of what? ArcTan of one argument has only one argument andhow can that be reversed? What has two arguments is the coordinatespecification {x, y} and they are not reversed in ArcTan[x, y].

It is the one argument form ArcTan[y/x] that seems poorly designed and wouldprobably only be used when one knows the quotient and not x and y - so therewouldn't be anything to reverse.